Bright and Fast‐Response Hybrid X‐Ray Scintillators by Molecular and Dielectric Confinement

Scintillators featuring bright and fast-response properties are essential for high-speed and dynamic X-ray imaging. Nevertheless, simultaneously possessing high light yields and fast-response remains a significant challenge for most scintillators. Herein, we propose a strategy to achieve the bright and fast-response characteristics of scintillators by leveraging the combined effects of dielectric and molecular confinement in organic-inorganic hybrid scintillators (TPA)₂MnBr₄. Thereinto, large tetrapropylammonium cations (TPA⁺) surround [MnBr₄]^2- units, forming a zero-dimensional (0D) molecular confinement structure that promotes electron localization and achieves a notable light yield of 56800 photons MeV^-1. Meanwhile, the low dielectric constant of TPA⁺ can enhance dielectric confinement of [MnBr₄]^2- units, mitigating exciton capture by deep defects. These synergistic effects in the scintillators lead to a large exciton binding energy of 1028.8 meV and an ultrafast response time of 500 fs. Notably, under the irradiation of X-rays, (TPA)₂MnBr₄ exhibits an extremely low detection limit of 18.7 nGy_air s^-1 and an exceptional spatial resolution of 21.0 lp mm^-1. Given the bright and fast-response features of scintillators, we demonstrate the potential applications in 3D dynamic and real-time X-ray imaging. These findings lay the groundwork for designing high-performance scintillators and open avenues for innovative applications in high-resolution and dynamic imaging.